The present invention relates to hot water supply systems and, more particularly, to a versatile hot water supply system incorporating a vapor generator.
Hot water systems of conventional design generally incorporate a feedwater boiler where large amounts of cold water are stored and heated to a selected temperature which depends upon demand requirements. Such applications include industrial hot water feed lines, schools and office buildings and commercial hot water markets such as car washes and airports. Water demand generally fluctuates in such instances and much energy can be lost from heating large boilers during time of inactivity. Commercial hot water markets may include construction sites in locations often not accessible to utility lines. This presents the obvious problem of how to heat the water.
Various prior art embodiments have addressed the need for versatile hot water supply systems which meet the needs of intermediate flow demands and remote utilizations. Certain prior art systems have incorporated "in-line", electrical heating elements which directly engage the high pressure water flow along a select flow path for heating the water to a select temperature as it passes through the heater. Problems of cost, fuel energy conservation and limited demand capacity have been found to be prevalent in such systems.
Industrial applications which are remotely disposed from power utility systems present a myriad of additional problems for efficient hot-water systems. Concrete batching plants for example, are generally used in areas not having hot water, much less energy supply lines. Such applications include concrete paving of remote areas and/or the building of concrete structures. Hot water boilers and/or other prior art hot water heating elements are of extremely limited use in such markets. While combustion fuel is, or may be plentiful, means for safely and efficiently utilizing combustible fuel to meet varying hot water supply demands is severely limited by prior art designs.
One difficulty encountered in combustion fuel hot water supply units of the prior art is the high carbon monoxide content in the end product. This difficulty is particularly prevalent in prior art fuel vaporizers. Such noxious vapor content is objectionable around human occupation; a generally occurring condition where hot water is needed. High carbon monoxide production is traceable to incomplete combustion, in the main, which is in turn traceable, in part, no difficulties in maintaining stable flames in most prior art vaporizing units. Excessive quenching of flames through direct radiative and convective contact between the flame and the feedwater is often the cause. The advantages that vapor generators might have in hot water supply systems have been overlooked in light of these problems and in view of the low pressure steam produced. To be effective, low pressure steam must be automatically convertible to high pressure hot water upon demand. Prior art systems have not shown such capabilities and these hot water supply problems still exist.
The method and apparatus of the present invention address such hot water supply needs and overcomes the problems of the prior art by providing a low pressure, vapor generator in which a demand sensitive product stream substantially free of carbon monoxide and other deleterious end use gases is produced. The vapor generator of the present invention may also be used in remote areas to produce a water-steam product at a sufficiently high heat energy state to convert large cold water supplies relatively quickly into hot water at either low or high pressure.